Campaign posters and billboards proliferate ahead of Nigeria's main parties' primaries

Nigeria's main political parties are gearing up to hold primaries this weekend to elect their candidates for the presidential race.

The face on campaign posters and billboards of the All Progressives Congress party's Bola Tinubu has been greeting commuters in Abuja and Lagos for months.

Known locally as the "Godfather of Lagos he is confident of finally achieving his presidential ambition in the 2023 election. But he is just one in a packed field of high-profile potentials still scrambling for position. may be

For the APC, Tinubu faces rivalry from former ally and Vice President Yemi Osinbajo who has been touting his experience helping run the federal government.

Tinubu and Osinbajo, who once worked together in Lagos State, have busily canvassed support from governors and local delegates in recent weeks.

Rotimi Amaechi, who recently resigned as Buhari's transport minister and who is from Nigeria's southern oil region, is also challenging the two top APC players.

The opposition People's Democratic Party candidates include perennial challenger Atiku Abubakar who will be on his sixth attempt to run for the presidency. He has been promising a firm hand to end insecurity if elected.

Challenging him are Bukola Saraki, a former senate president, and Aminu Tambuwal, the Sokoto State governor who enjoys strong support in mostly Muslim northern Nigeria.

PDP also has a southern Christian candidate in Ezenwo Nyesom Wike, governor of Rivers State. He is also a financier of the PDP and influential in the party.

Deciding the APC and PDP candidates settles who will be the likely favourite to replace President Muhammadu Buhari. The former military commander is stepping down after two terms.

Buhari, 79, leaves office with Nigeria still struggling with a jihadist conflict in its northeast and violent banditry and kidnapping in its northwest.

Africa's largest economy is also dealing with the double hits of the coronavirus pandemic and the Ukraine war that have pushed up fuel and food prices across the continent.

All eyes will be on Buhari to see whom he endorses and whether he will push the APC to accept a consensus candidate.

He has also yet to approve an amendment to a new election law, which analysts say is clouding the way some delegates can vote for candidates in the primaries.

Since a return to democracy from a military dictatorship in 1999, Nigeria has held six national elections which were often marred by fraud claims, technical difficulties, violence and legal challenges.

Under an informal agreement among the political elite, Nigeria's presidency is usually alternatively "zoned" between candidates from the north and the south.

After eight years under northerner Buhari, most agree the presidency should now go to a candidate from the south.

Rotating power in federal government has been seen as a balancing force in a country almost equally divided between the mostly Christian south and predominantly Muslim north.

Tinubu is a southern Muslim, Osinbajo is a southern Christian and Amaechi is also from the south as a former governor of oil-wealthy Rivers State.

But Ahmed Lawan, current Senate president and a northern Muslim, also recently joined the APC race, raising questions about support from powerful APC northern strongholds.

Major PDP main candidates Abubakar and Tambuwal are also northerners, prompting speculation the opposition party may ditch the "zoning" tradition and go for a candidate from Nigeria's north.